Method of preparing pulp



Patented ay 1 5, 1923.

ssn

TENT OFFICE.

CARL BACHE-WIIG, OF PORTLAND, MAINE; BERTHA M. BACHE-WIIG EXECUTRIX OESAID CARL BACHE-WIIG, DECEASED.

METHOD PREPARING PULP.

1T0 Drawing. Application filed April 27, 1918, Serial No. 231,204.Renewed December 22, 1919. Serial To (ZZZ whom it may concern:

Be it known that I, CARL BACHE-VIIG, a citizen of the United States,aresident of Portland, in the county of Cumberland and State of Maine,have invented an Improvement in Methods of Preparing Pulp, of

which the following is a specification.

This invention has-for its object the production of pulp by a novelmethod, from straw, corn-stalks, wood, baggasse and simiare disclosed inmy Patent No. 1,327,221,

issued January 6, 1920.

l\Iy novel metliod'involies two treatments which are preferably carriedon successively.

By my first treatment the cellulosic material composing the pulp issoftened, that isto say, its ligneous matter is softened but notdestroyed and its fibers are swollen and caused to separate.

In carrying out the first treatment I may proceed as follows :thematerial or ,substance employed, in small pieces, or cutinto suitableshort lengths, is placed in a tank or digester, which may be open orclosed, and a softening agent. a solution of sodium chloride. (NaC-l) isadded, as for instance, I may add water containing from one half of oneto three percent of sodium chloride; and then heat the mass to atemperature of from C; to 110 C. for from 12 to' 72 hours, thetemperature and time being more or less variable depending on thematerials used and the strength thereof. yet it will be understood thatordinarily the higher the temperature, the shorter the time required,and vice versa During this first treatment the ligneous matter andfiber, are acted upon and gently softened but not destroyed.

The ligneous matter may be utilized subsequently in the composition ofthe paper, so that the loss in weight is immaterial and the result is avery large yield. v

Moreover, the pieces are more or less saturated with the solution, whichsolution is further utilized in the performance of the second treatmentof my method.

The solution is then drawn off or removed.

' The same solution may be used repeatedly as a softening agent for alarge number of times, if desired, and in such case it becomes quiterich in potash which is extracted from the cellulosic substancesufficiently to admit of the potash being claimed by evaporation orother means for commercial purposes.

The second treatment; The mass having been thus treated is then cookedwith a bisulphitepulp forming liquor, or a sodium chloride solutiondepending upon which kind of paper the pulp is to be used for.

For instance, when during the firsttreatment a sodium chloride solutionis employed, then, during the second treatment a bisulphite liquor maybe employed and pulp for a fine grade of paperwill be produced whichwill be suitably bleached.

The strength of the bisulphite solution will be such, together with .thetime and temperature of cooking that the fiber will not be destroyedoutside of the fiber walls as usually is the case in the ordinaryprocesses.

The first treatment only softens the ligneous matter and the fiber andtherefore a weak solution can be used on the second treatment thusretaining all the fiber in the material treated.

This second treatment may continue for a period of time, say from 6 to12 hours,- at a temperature of from110 degress C. to 130 degrees C. butthe longer the period of time There is a physical reaction between thesoftening agent, as sodium chloride, with which the mass is saturatedduring the first treatment, and the pulp forming agenteniployed' as thebisulphite liquor employed during the second treatment, to which Iattribute, at least in part, some of the advantages gained by thisprocess.

On account of the first treatment, as aforesaid, a weaker pulp formingagent may be employed in the second cooking operation,

and also alower temperature and a shorter period of time than under anyof the methods known to me.

By this process a good news print paper may be produced with strawalone.

1.- The method of treating straw, cornstalks and other cellulosicsubstances for the preparation of pulp for paper which c0nsists in twosuccessive treatments, first, treating the material with sodium chlorideto soften but not destroy the ligneous matter, and second, cooking thetreated mass with a bisulphite pulp forming liquor of such strength thatthe fiber'will not be destroyed.

2. The method of treating straw, cornstalks and other cellulosicsubstances for the preparation of pulp for paper which con sists intreating the material with sodium:

chloride to soften but not destroy the ligneous matter and subsequentlycooking the mass with a bisulphite pulpforming liquor of such strengththat the fiber will not be destroyed.

3. The method of treating straw, cornstalks and other cellulosicsubstances for the preparation of pulp for paper which consists in twosuccesslve treatments, first, treating the material with sodium chlorideto soften but not destroy the ligneous matter,

and to extract potash from the cellulosic substance, then drawing oilthe softening agent containing the potash and then cooking the mass. v v

In testimony whereof, I have signed my name to this specification, inthe presence of two subscribing witnesses.

CARL BACHE-WIIG.

Witnessesi CHARLES DUMMOND,

WADLEIGH B/DUMMOND.

